在一个生态系统中, A种群有10个个体, B种群有100个个体, C种群有1000个个体, D种群有10000个个体,则它们的食物链关系是(　    )

酚酞（C₂₀H₁₄O₄）是一种常用的化学试剂，下列关于酚酞的说法正确的是（   ）

     Mary likes dogs very much. She has a pug-dog. It is white. It has big eyes and ears. It is small but it is cute and beautiful.
    Every morning, the dog eats some bread and meat. They are the dog's favorite food. When Mary goes to school, the dog always waits for(等待) her at the gate. When she comes back home, the dog follows her here and there. When Mary does her homework, it lies(卧) near her feet. When Mary watches TV, the dog sits on the sofa near her. When Mary goes to bed, the dog lies its bed next to Mary’s. in the evening, they often run and play in the yard (院子). They are really good friends. 
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